Ok, so i downloaded my checklist and was going to do everything by the book. I brought my boat to the lake, added stabil, let it come to temp and pushed the throttle down for a few minutes. within a minute or two after doing so the "check engine" light comes on. Gauges were normal, operating temp where it should be. Oil pressure good, voltage good, so I shut it down and started it back up, light goes off, I idle for a minute (heading back towards the dock) and again pushe the throttle down. It does the same thing. By now Im back at the dock so I shut it down, pull it out and drain the block right there at the ramp, like was mentioned earlier in this thread, and when I drained the exhaust manifolds pieces of the impeller came out. I pulled the cover off and three of the rubber fins were missing. I had it kchecked out before I bought it and it checked out fine with the exception of the energy absorbers and the trailer brakes. I put ten hours on it only. My question is, is there any damage that could have happened, and should I worry about the impeller pieces clogging any of the passages? Also, I took off all the hoses and the port drainplug to drain the block, however on the starboard side there was not a plug, but the knock sensor. Am I to assume that the knock sensor is the plug? I looked all around and didnt see a block drain. Any advice would be appreciated.

What do you mean by "I pushed the throttle down"? It was at idle, or WOT? If it's the LT-1, you don't want to idle for a long time.

Yes, look in the thermostat housings and see if you can find pieces of the impeller.

How long have you owned this boat? If it's new to you, buy two impellers WITH THE GASKETS and keep one on-board at all times, as a spare. The knock sensor is the plug for that side and the other has either a petcock, a plug or a T-fitting for a heater. Remove whatever is there and make sure the water rushes out, not at slow dribble. You also need to remove the plugs or disconnect the hoses on the rear of the exhaust manifolds, the oil cooler and at the lowest points of the pumps, then crank it over with the lanyard off.

What do you mean by "I pushed the throttle down"? It was at idle, or WOT? If it's the LT-1, you don't want to idle for a long time.

Yes, look in the thermostat housings and see if you can find pieces of the impeller.

How long have you owned this boat? If it's new to you, buy two impellers WITH THE GASKETS and keep one on-board at all times, as a spare. The knock sensor is the plug for that side and the other has either a petcock, a plug or a T-fitting for a heater. Remove whatever is there and make sure the water rushes out, not at slow dribble. You also need to remove the plugs or disconnect the hoses on the rear of the exhaust manifolds, the oil cooler and at the lowest points of the pumps, then crank it over with the lanyard off.

Quite honestly i idled for about 40 minutes or so, as it was a beautiful morning, I was enjoying my coffee and it was the last time it was going to be in the water. I just bought the boat about a month ago and put about ten hours on it. I had it checked at the Mastercraft dealer and it checked out fine, including the impeller. I do know about the impeller and asked at the time that it was cecked out if it should be replaced, however the service manager said that because it was the end of the season not to worry about it, but to just keep an eye on the temp gauge for any sudden fluctuation, but replace it when I winterized it. I did not know that the boat was not meant to idle long. What damage occurs with excessive idle time? We actually use it for more than just skiing and probably 2 of the ten hours have been at idle while driving around the lake watching the sunset. I removed everything thus far but have not cranked it over. I was going to change the oil, and tranny fluid, fog it and then crank it over as the last thing that I did. I pulled the entire drain plug out on the block, as I am aware how the passages get clogged with debris. Am I to worry about the pieces of impeller that may or may not be in the block, or are the passages large enough so that the flow will not be restricted?

Quite honestly i idled for about 40 minutes or so, as it was a beautiful morning, I was enjoying my coffee and it was the last time it was going to be in the water. I just bought the boat about a month ago and put about ten hours on it. I had it checked at the Mastercraft dealer and it checked out fine, including the impeller. I do know about the impeller and asked at the time that it was cecked out if it should be replaced, however the service manager said that because it was the end of the season not to worry about it, but to just keep an eye on the temp gauge for any sudden fluctuation, but replace it when I winterized it. I did not know that the boat was not meant to idle long. What damage occurs with excessive idle time? We actually use it for more than just skiing and probably 2 of the ten hours have been at idle while driving around the lake watching the sunset. I removed everything thus far but have not cranked it over. I was going to change the oil, and tranny fluid, fog it and then crank it over as the last thing that I did. I pulled the entire drain plug out on the block, as I am aware how the passages get clogged with debris. Am I to worry about the pieces of impeller that may or may not be in the block, or are the passages large enough so that the flow will not be restricted?

If it's a beautiful morning, why would you NOT take it out on the water? That speeds up the process and, well,...

If the service manager saw a damaged impeller and DIDN'T replace it, I'd be pretty PO'd. It was already out- what better time to do this? If you have three missing vanes, it can't cool the engine at idle, period. If ANY vanes were missing when the shop looked at it, I would have a serious problem and if they didn't document everything, they'd be on my S-list.

Look at it this way- the choices were to A) replace a bad impeller and you probably wouldn't have had this problem (assuming the oil cooler and raw water hoses are all clear of any obstructions) or B) leave it and let you have this problem. A costs a little but B could be expensive if the exhaust hoses are soft, the flappers and flanges are blistered and the engine cooks. If these aren't at least inspected, you're asking for trouble.

Yes, worry about the missing vanes. Never assume they're not going to cause a problem.

Look, I'm not trying to be the voice of doom and gloom but these are different from car engines because they have a raw water impeller that's not metal and can be damaged and they have rubber exhaust hoses and flappers & plastic exhaust flanges that can be melted by hot exhaust gases. If any water was going through the engine and exhaust, it's possible that they weren't damaged badly because you were only at idle but they still need to be checked and the dealer should have instructed you on what to do WRT long idle times (basically, "don't"). The oil cooler should be checked- if you find weeds and other debris, that's a likely cause for this problem.

If it's a beautiful morning, why would you NOT take it out on the water? That speeds up the process and, well,...

If the service manager saw a damaged impeller and DIDN'T replace it, I'd be pretty PO'd. It was already out- what better time to do this? If you have three missing vanes, it can't cool the engine at idle, period. If ANY vanes were missing when the shop looked at it, I would have a serious problem and if they didn't document everything, they'd be on my S-list.

Look at it this way- the choices were to A) replace a bad impeller and you probably wouldn't have had this problem (assuming the oil cooler and raw water hoses are all clear of any obstructions) or B) leave it and let you have this problem. A costs a little but B could be expensive if the exhaust hoses are soft, the flappers and flanges are blistered and the engine cooks. If these aren't at least inspected, you're asking for trouble.

Yes, worry about the missing vanes. Never assume they're not going to cause a problem.

Look, I'm not trying to be the voice of doom and gloom but these are different from car engines because they have a raw water impeller that's not metal and can be damaged and they have rubber exhaust hoses and flappers & plastic exhaust flanges that can be melted by hot exhaust gases. If any water was going through the engine and exhaust, it's possible that they weren't damaged badly because you were only at idle but they still need to be checked and the dealer should have instructed you on what to do WRT long idle times (basically, "don't"). The oil cooler should be checked- if you find weeds and other debris, that's a likely cause for this problem.

Im going to give the dealer the benefit of the doubt, as they have known the boat from day one, and the list of checks that they did were extensive and ranged from the trailer brakes to the energy absorbers holding up the engine cover. I found one of the vanes when I drained the port manifold and there are only two missing. While draining there was some crud that came out, so the other one could possibly be destroyed beyond the point of recognition. The temperature at the gauge never fluctuated, so Im fairly confident that there was no overheating. I am on my way out the door to finish the winterization, and am going to look for the debris you were talking about. Thanks for the pointers. I may be over anlalyzing this whole deal, however I have wanted this boat for over 6 years, and well frankly, its still new to me, i absolutely love it, and I plan on skiing the my a** off with it for years to come.

Im going to give the dealer the benefit of the doubt, as they have known the boat from day one, and the list of checks that they did were extensive and ranged from the trailer brakes to the energy absorbers holding up the engine cover. I found one of the vanes when I drained the port manifold and there are only two missing. While draining there was some crud that came out, so the other one could possibly be destroyed beyond the point of recognition. The temperature at the gauge never fluctuated, so Im fairly confident that there was no overheating. I am on my way out the door to finish the winterization, and am going to look for the debris you were talking about. Thanks for the pointers. I may be over anlalyzing this whole deal, however I have wanted this boat for over 6 years, and well frankly, its still new to me, i absolutely love it, and I plan on skiing the my a** off with it for years to come.

The problem with thinking that the engine didn't overheat because the temperature didn't spike is that the coolant temperature sensor needs to be immersed in liquid in order to work. If it was at a particular temperature and the liquid goes away, it won't cool down very fast because air doesn't conduct heat very well.

I just bought a 99 X Star (205 V) the guy I bought if from says I have the LT1 but I want to be sure, this would mean the difference between using RV anti freeze or not.
How can I tell if I have the LT1 or not?

I just bought a 99 X Star (205 V) the guy I bought if from says I have the LT1 but I want to be sure, this would mean the difference between using RV anti freeze or not.
How can I tell if I have the LT1 or not?

Thanks!

Is the engine all black, or does it have a large, metal part over the top with a rectangular plastic part to the side that has a hose clamp? The LT-1 would have black plastic pieces over the injectors with 'Corvette' on them.

If you don't have the black plastic covers and the intake manifold is narrow with the throttle body in the center but it doesn't look like a carb on top, you have the LTR, which is also a really good engine.